1. Technical Field
The technology of this disclosure pertains generally to microelectromechanical systems (MEMS) resonators or “resoswitches”, more particularly to MEMS resoswitches that can be excited by direct radio frequency (RF) inputs, and still more particularly to MEMS resoswitches that can listen for valid input signals without the need for DC power draw.
2. Background Discussion
This disclosure describes a method and an apparatus for realizing a zero quiescent power trigger sensor and transceiver based on a microelectromechanical resonant switch. This receiver is unique in its use of a resonant switch (“resoswitch”) to receive an input, amplify it, demodulate it, and finally deliver power to a load. During this process, power is consumed only when a valid input signal within the passband of the resonant element actuates the structure with sufficient amplitude to cause switch impacting. In other words, when actively receiving data, power is required; when listening in a standby (or quiescent) state, no DC power is needed.
In traditional engineering, many physical terms are neglected and assumed to be zero, when in fact they actually are not. However, to make engineering analysis practical, all of these not-quite-zero terms are neglected. For instance, when two disconnected printed circuit board traces are unconnected in any manner, and supplied with DC voltage, the typical assumption is that there is zero power dissipated. In this technology, electret comb fingers are electrically isolated at different potentials. Much like the previous printed circuit board traces, the assumption is that zero power is dissipated.
In the case of the resoswitch, this means that almost no quiescent power is consumed when switching is not occurring, i.e., essentially no power is consumed while listening in standby.
This technology may reduce power consumption while also raising robustness against interferers, enabling sensor wireless communication performance many times better than presently available. The power reductions are such that there might never be a need to replace a battery over the lifetime of a given sensor. Given the prediction that over a trillion sensors will be needed for the internet of things, this technology will likely play a key role in future sensor implementations.
This technology may also have significant near term impact, since its ability to channel-select should greatly improve short range communication applications. For example, with this technology, interference between Bluetooth devices could become a thing of the past. Miracast would work, despite the presence of interfering Bluetooth signals.
The widespread expectation that autonomous sensor networks will fuel massively accessible information technology, such as the Internet of Things (IoT), comes with the realization that huge numbers of sensor nodes will be required, perhaps approaching one trillion. Needless to say, besides cost, energy will likely pose a major constraint in such a vision.
In particular, for autonomous sensor networks that are remotely controlled, an extremely high percentage of time is spent listening for externally RF transmitted control signals. Power dissipation in such instances may be driven significantly by input receiver quiescent power demands.